Hess's Law

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kanikubari
Posts: 30
Joined: Fri Dec 07, 2018 12:18 am

Hess's Law

Postby kanikubari » Sun Feb 03, 2019 10:08 pm

How do you use Hess's law to find the reaction enthalpy? 8.61, 4D.19?

Giselle1B
Posts: 26
Joined: Fri Sep 28, 2018 12:19 am

Re: Hess's Law

Postby Giselle1B » Sun Feb 03, 2019 10:54 pm

For Hess' law, think of it as manipulating equations in order to add up their delta H's. Here is a link to a video that explains it way better than me: https://www.youtube.com/watch?v=2q2u5sj4V00.

josephperez_2C
Posts: 70
Joined: Wed Nov 15, 2017 3:04 am

Re: Hess's Law

Postby josephperez_2C » Sun Feb 03, 2019 11:23 pm

Hess's law basically states that enthalpy changes are additive. Enthalpy change at each step of a multi-step reaction can be added to give Total Enthalpy Change.

Nathan Tran 4K
Posts: 92
Joined: Fri Sep 28, 2018 12:16 am

Re: Hess's Law

Postby Nathan Tran 4K » Sun Feb 03, 2019 11:32 pm

Hess's Law allows us to manipulate equations where one constituent appears in one equation's reactants while the same constituent appears in another equation's products. As such, you can cancel out the constituent by adding the equations together. In doing so, you must also add up the enthalpies. In adding the equations together, you are trying to get an equation that matches the equation of a reaction where you are looking for its enthalpy.


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